It is our purpose to understand how cellular systems by responding to environmental stimuli exercise genetic control over the synthesis and assembly of cellular membranes. Because of the gratuitous nature of the inducible photosynthetic membrane system of the facultative photoheterotroph, Rhodobacter sphaeroides and the roles of oxygen and light in its synthesis, this system has been chosen for detailed molecular genetic study. Four major specific aims, involving genetic, biochemical a molecular analyses of the four known cellular transcriptional regulatory pathways affecting inducible membrane formation in response to oxygen and light, namely: the FnrL regulon; the two component activation, Prr regulon; the repressor PpsR- anti- repressor AppA regulon; and the outer membrane localized TspO regulon, will all be analyzed. In addition, how each of these regulatory pathways interfaces with one another, and how each is integrated into the overall cellular economy will remain, focus of these studies. In all of these studies, the importance of redox-generated signaling will be emphasized as the means through which environmental stimuli are converted to cellular action. A fifth specific aim, directed at our analysis of the post-transcriptional regulation of integral membrane protein complex assembly will also be investigated as such studies derive from the original four specific aims. The ubiquitous nature of redox signaling and the essential role(s) of cellular membranes in energy generation and homeostasis have profound implications for human health. We specifically address here issues for our consideration of the mitochondrial localized peripheral benzodiazepine receptor and its functional and structural counterpart in Rhodobacter sphaeroides. We show that the bacterial and mammalian proteins are interchangeable and thereby permits us to understand the structure and function of the mammalian protein by exploiting the bacterial model. This receptor is pharmacologically of major importance in drug binding, but its physiological role remains to be determined.